The present invention pertains generally to disc brakes for automotive use, and more particularly to a new and improved power-operated, failsafe braking system.
Heretofore, hydraulically operated disc brakes have been restricted to normal service operation, in which the operator applies the brake by applying foot pressure to a brake pedal. For parking or emergency brake purposes, an entirely separate brake is generally used, which may consist of either a disc brake or a drum brake mounted on the drive shaft or on the wheel axles. The provision of separate parking brake units adds to the vehicle cost and maintenance, and such independent brake systems frequently deteriorate if not used regularly, as in flat country where drivers commonly use the transmission pawl as a parking brake. Rust and dirt accumulate on the linings and prevent the brakes from functioning properly when needed to park on a slope or in an emergency.